He stands half in and half out of the world; he is the men,
But he cannot see below Fuji
The shore the color of sky; he is the wave, he stretches
His claws against strangers.
In this part of the second stanza the poet describes how the wave is so big that Fuji cannot be seen, the only thing that can bee see is the wave that “stretches his claws” this is definitely, a threating imagery, picturing claws stretched toward you, the details in these lines is the excerpt that best supports the intention of the artist to made the wave to feel threatening.